I don't wish to charge and deliver the subscription on the initial purchase.

You could achieve this with a workaround. You should be able to set the subscription discount to 100%, then set the Automated Discount modification to apply after initial purchase and set the discount to whatever you would like.
That way your customers shouldn't get billed in the initial purchase. You could tag the initial orders in our app settings, so that you know which orders to ignore in the orders tab.

This is similar to how you can set up a free trial, which we described here: https://www.sealsubscriptions.com/articles/how-to-offer-free-trial